The present invention relates to railroad freight cars including wells for carrying intermodal cargo containers, and relates particularly to lengthening existing container well cars to carry containers of a greater length.
Many railroad freight cars were built over a period of several years, beginning in the 1980's, to be able to carry intermodal cargo containers 48 feet long, as well as containers of the international standard 40-foot length, in container wells defined between deep side sills of the car bodies. Railroad cars of this type are disclosed in U.S. Pat. Nos. 5,611,285 and 5,170,718, for example. Many of such 48-foot well cars were built as multi-unit cars, each usually having five container-well car units permanently coupled together.
Recently, longer containers such as nominal 53-foot containers have largely replaced 48-foot containers. Many 48-foot well car units that are still several years away from being worn out are now idled, because there are now too few 48-foot containers being moved. Since 48-foot well cars cannot accept the 53-foot containers except stacked atop shorter containers carried in the well, and since new 53-foot well car units are very costly, it is now desired to extend the length of some of the existing 48-foot well cars to enable them to carry 53-foot containers in the well.
Because a longer car body requires greater clearance at mid-length between the bottom of the car body and the rails than does a shorter car body, provision must be made to ensure ample clearance in the center of a lengthened car.
What is needed, then, is an economical method for lengthening container-well units of railroad freight cars, and a resulting strong, long-lasting, dependable, lengthened container-well car unit structure capable of carrying 53-foot containers efficiently over a further lifetime of several years.